The present invention relates to an apparatus and method for inducing sputum samples from a patient. In particular, the present invention relates to obtaining high quality sputum samples for diagnosing pulmonary disorders, especially lung cancer.
Lung cancer has a survival rate of only 14% and is the leading cause of cancer death in the United States. The poor prognosis for lung cancer is related to both the lack of effective early detection methods, and the inability to precisely locate the diseased area of the lung to be treated. However, improved imaging techniques now allow much better tumor location capabilities, once detected, to allow specific treatment even at very early stages.
A cooperative trial undertaken by Johns Hopkins Oncology Center, Memorial Sloan-Kettering Cancer Center, and the Mayo Clinic utilized sputum induction as an early screening method to determine if a reduction in lung cancer deaths could be achieved. This study showed the resectability and survival rates among the study group were higher than among the control group, but the mortality rates were not reduced. This result led health policy groups to conclude that this type of screening method could not be justified.
These findings discouraged further research using sputum cytology for early cancer detection. Recent findings in lung tumor biology research renewed interest in the use of noninvasive techniques for screening. Biomarkers which indicate phenotypic and genotypic abnormalities and track the transformation of bronchial epithelium into a malignant tumor have been found. Sputum samples are prime candidates for diagnosing cancer with biomarkers, because it is believed that exfoliated epithelial cells recovered in sputum samples may provide the earliest indicators of lung cancer. A number of molecular genetic techniques have provided evidence that biomarkers can be detected in sputum.
Studies utilizing computer assisted, high-resolution image analysis have detected changes associated with cell transformation in normal appearing sputum samples, and also squamous cell carcinomas were detected in otherwise normal appearing epithelial cells. In addition, a number of monoclonal antibodies have been used to detect tumor-associated surface antigens on bronchial epithelial cells prior to the development of a pulmonary neoplasm. These types of studies strongly indicated that sputum cytology had the potential to improve the sensitivity, specificity, and predictive value for early diagnostic screening.
The major flaw with these methods was that repeat samplings were required to ensure adequate samples for analysis which is costly and jeopardizes a timely diagnosis. Two methods have commonly been used to collect sputum. One method uses ultrasonic nebulizer treatments to provide a mild bronchial irritant which induces a cough and supplies moisture to facilitate mucus passage. The other method is an early morning cough technique to collect samples. Four independent studies were performed which utilized the two collection methods and tried to determine whether either or both would be adequate and, therefore, useful for early diagnostic screenings. The results, however, were inconclusive.
Thus, a new method is needed to produce reliable samples while minimizing repeat sampling. This method could also be utilized to evaluate other pulmonary disorders and diseases such as asthma, chronic obstructive pulmonary disease (COPD), tuberculosis, Pneumocystis carinii pneumonia (PCP), inflammation, and infection by morphologic, immunochemical, fluorescence, molecular, or genetic techniques.
A vest apparatus has been used by clinicians to facilitate mucus passage for patients with pulmonary disorders. The most widely used device is the ABI Vest Airway Clearance System by American Biosystems, the assignee of the present application. The apparatus compresses the chest at an alternating frequency faster than breathing which increases airflow velocity, creates cough-like shear forces, decreases the viscosity of mucus, and increases mucus mobilization. This apparatus, until now, has only been used therapeutically for patients with problems such as cystic fibrosis and asthma.